ALKBH10B-mediated m6A demethylation is crucial for drought tolerance by affecting mRNA stability in Arabidopsis

Abstract

N6-methyladenosine (m6A) is the most abundant modification found in eukaryotic mRNAs. The methyltransferases (“writers”) and demethylases (“erasers”) add and remove m6A marks, respectively, which controls transcriptome-wide m6A levels and plays crucial roles in plant development and response to environmental cues. The alpha-ketoglutarate-dependent dioxygenase homolog 10 (ALKBH10) is the first confirmed plant m6A eraser and is involved in floral transition in Arabidopsis (Arabidopsis thaliana). Recent studies showed that ALKBH10B is also involved in the Arabidopsis response to salt, drought or ABA. However, the molecular mechanism underlying the ALKBH10B-guided drought tolerance has not yet been explored. In this study, we investigated how ALKBH10B-mediated m6A demethylation confers drought tolerance in Arabidopsis. The alkbh10b mutants were sensitive to drought stress, whereas the ALKBH10B-overexpressing plants were tolerant to drought stress. Notably, under dehydration stress, the m6A levels of several drought stress positive effectors were elevated in the alkbh10b mutants, and their transcript abundance was lower in the mutants but higher in the transgenic lines. Importantly, the decay rates of these m6A-modified transcripts were significantly higher in the alkbh10b relative to the wild-type under dehydration stress. Collectively, these findings establish a molecular link between ALKBH10B-guided m6A demethylation and mRNA stability control in drought stress tolerance.